[pitivi] flatpak: Fix build inside gnome-builder

[Thibault Saunier <tsaunier src gnome org>]

commit 8e86c8d0bfe298ba57bdffd981ad3c235ccdae6f
Author: Thibault Saunier <tsaunier igalia com>
Date:   Thu Feb 22 10:47:04 2018 -0300

    flatpak: Fix build inside gnome-builder
    
    Fore some reason submodule cloning fail if they are not specified in the sources

 build/flatpak/org.pitivi.Pitivi.json | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)
---
diff --git a/build/flatpak/org.pitivi.Pitivi.json b/build/flatpak/org.pitivi.Pitivi.json
index 62530b73..94038fd3 100644
--- a/build/flatpak/org.pitivi.Pitivi.json
+++ b/build/flatpak/org.pitivi.Pitivi.json
@@ -430,11 +430,23 @@
             "builddir": true,
             "config-opts": ["-Ddisable_gtkdoc=true", "--libdir=lib"],
             "sources": [
+               {
+                    "type" : "git",
+                    "branch" : "master",
+                    "disable-shallow-clone": true,
+                    "url" : "git://anongit.freedesktop.org/gstreamer/gst-libav"
+                },
                 {
-                    "type": "git",
-                    "branch": "master",
-                    "url": "git://anongit.freedesktop.org/gstreamer/gst-libav",
-                    "disable-shallow-clone": true
+                    "type" : "git",
+                    "url" : "https://git.ffmpeg.org/ffmpeg.git";,
+                    "disable-shallow-clone": true,
+                    "branch" : "master"
+                },
+                {
+                    "type" : "git",
+                    "url" : "git://git.libav.org/gas-preprocessor.git",
+                    "disable-shallow-clone": true,
+                    "branch" : "master"
                 }
             ]
         },